Present drilling fluids for deep water wells have severe degenerative effect on the environment with high operational and disposal costs.Thus,making them less desirable in recent times.Ester synthetic drilling fluid p...Present drilling fluids for deep water wells have severe degenerative effect on the environment with high operational and disposal costs.Thus,making them less desirable in recent times.Ester synthetic drilling fluid provides a novel environmentally friendly alternative but conventional ester-based drilling fluids exhibit high viscosities in deep-water wells causing excessive equivalent circulating density(ECD)and increased risk of lost circulation owing to narrow mud density window.This study experimentally investigates the critical fluid properties and aerobic biodegradability potentials of two newly developed deep-water synthetic ester drilling fluids namely:iso-propyl caprylate(COIPE)and iso-propyl linolenate(LOIPE)synthetic fluids and their comparison with synthetic-paraffin(SP-SBF)and isomerized-olefin(IOSBF)synthetic hydrocarbon fluids.The esters of iso-propyl caprylate and iso-propyl linolenate were produced from the isolation of ester mixtures that were obtained from the homogeneous catalytic transesterification of coconut and linseed plant oil biomass respectively.The COIPE was isolated from the coconut oil iso-propyl ester mixture by low-pressure fractional distillation technique.While fractional distillation and crystallization were used to isolate the LOIPE ester from the linseed oil iso-propyl ester mixture.Meanwhile,the aerobic biodegradation investigation was conducted by a modified oxygen consumption respirometry technique.The GC-MS analysis of the COIPE and LOIPE showed that the former contains essentially of lower saturated carbon compounds(C8).Whereas the latter contains higher molecular weight and unsaturated carbon compounds(C18+).The COIPE and LOIPE kinematic viscosity values are in good agreement with that of the reference synthetic hydrocarbon fluid samples(SP-SBF and IO-SBF).Although,the COIPE synthetic ester has lower viscosity value owing to the presence of shorter chain and saturated carbon atoms(C8 esters).Similarly,the linolenic oil iso-propyl ester has excellent cold flow characteristics for deep-water well drilling owing to lower values of cloud and pour points as a result of higher concentration of poly-unsaturated linolenic esters.The iso-propyl caprylate and the iso-propyl linolenate ester synthetic fluids are readily biodegradable in the sea water inoculum under aerobic condition.However,the iso-propyl caprylate is inherently biodegradable because its degradation level and that of the reference chemical sample were already above 60%during the 10-day window period.The SP-SBF and the IO-SBF synthetic fluids have lower aerobic biodegradation values because they contain little quantity of poly aromatic hydrocarbons as evident in their GC-MS profiles.Finally,esters and unsaturated synthetic-based fluid are more rapidly biodegradable than paraffinic synthetic fluids and the rate of biodegradation of organic compounds decreases as molecular weight increases.展开更多
氨基酸稳定氮同位素(δ^(15)N)分析能准确有效地评估生物体的营养级以及氮在食物链中的流动。本研究优化了氨基酸氮同位素的分析方法:样品在酸性条件下水解后,释放出的蛋白质氨基酸经阳离子交换树脂纯化后,衍生为对应的N-新戊酰基,O-异...氨基酸稳定氮同位素(δ^(15)N)分析能准确有效地评估生物体的营养级以及氮在食物链中的流动。本研究优化了氨基酸氮同位素的分析方法:样品在酸性条件下水解后,释放出的蛋白质氨基酸经阳离子交换树脂纯化后,衍生为对应的N-新戊酰基,O-异丙醇(N-pivaloyl-isopropyl,NPP)酯,利用气相色谱-燃烧-同位素比值质谱仪(Gas chromatography-combustion-isotope ratio mass spectrometry,GC-C-IRMS)测定其δ^(15)N。经非极性气相色谱柱DB-5ms分离后,13种氨基酸NPP酯衍生物均可得到良好的基线分离。在样品量不低于20 ng N条件下,GC-C-IRMS方法的精密度优于1‰,测得的δ^(15)N值与EA-IRMS法测得的δ^(15)N值没有明显差异。阳离子树脂纯化前后各氨基酸δ^(15)N值差异低于1‰,表明没有产生明显的同位素分馏。采用本方法成功地估算了阿哈湖生态系统中常见水生生物的营养级,可作为研究氨基酸代谢以及生态系统特征的新方法。展开更多
文摘Present drilling fluids for deep water wells have severe degenerative effect on the environment with high operational and disposal costs.Thus,making them less desirable in recent times.Ester synthetic drilling fluid provides a novel environmentally friendly alternative but conventional ester-based drilling fluids exhibit high viscosities in deep-water wells causing excessive equivalent circulating density(ECD)and increased risk of lost circulation owing to narrow mud density window.This study experimentally investigates the critical fluid properties and aerobic biodegradability potentials of two newly developed deep-water synthetic ester drilling fluids namely:iso-propyl caprylate(COIPE)and iso-propyl linolenate(LOIPE)synthetic fluids and their comparison with synthetic-paraffin(SP-SBF)and isomerized-olefin(IOSBF)synthetic hydrocarbon fluids.The esters of iso-propyl caprylate and iso-propyl linolenate were produced from the isolation of ester mixtures that were obtained from the homogeneous catalytic transesterification of coconut and linseed plant oil biomass respectively.The COIPE was isolated from the coconut oil iso-propyl ester mixture by low-pressure fractional distillation technique.While fractional distillation and crystallization were used to isolate the LOIPE ester from the linseed oil iso-propyl ester mixture.Meanwhile,the aerobic biodegradation investigation was conducted by a modified oxygen consumption respirometry technique.The GC-MS analysis of the COIPE and LOIPE showed that the former contains essentially of lower saturated carbon compounds(C8).Whereas the latter contains higher molecular weight and unsaturated carbon compounds(C18+).The COIPE and LOIPE kinematic viscosity values are in good agreement with that of the reference synthetic hydrocarbon fluid samples(SP-SBF and IO-SBF).Although,the COIPE synthetic ester has lower viscosity value owing to the presence of shorter chain and saturated carbon atoms(C8 esters).Similarly,the linolenic oil iso-propyl ester has excellent cold flow characteristics for deep-water well drilling owing to lower values of cloud and pour points as a result of higher concentration of poly-unsaturated linolenic esters.The iso-propyl caprylate and the iso-propyl linolenate ester synthetic fluids are readily biodegradable in the sea water inoculum under aerobic condition.However,the iso-propyl caprylate is inherently biodegradable because its degradation level and that of the reference chemical sample were already above 60%during the 10-day window period.The SP-SBF and the IO-SBF synthetic fluids have lower aerobic biodegradation values because they contain little quantity of poly aromatic hydrocarbons as evident in their GC-MS profiles.Finally,esters and unsaturated synthetic-based fluid are more rapidly biodegradable than paraffinic synthetic fluids and the rate of biodegradation of organic compounds decreases as molecular weight increases.
文摘氨基酸稳定氮同位素(δ^(15)N)分析能准确有效地评估生物体的营养级以及氮在食物链中的流动。本研究优化了氨基酸氮同位素的分析方法:样品在酸性条件下水解后,释放出的蛋白质氨基酸经阳离子交换树脂纯化后,衍生为对应的N-新戊酰基,O-异丙醇(N-pivaloyl-isopropyl,NPP)酯,利用气相色谱-燃烧-同位素比值质谱仪(Gas chromatography-combustion-isotope ratio mass spectrometry,GC-C-IRMS)测定其δ^(15)N。经非极性气相色谱柱DB-5ms分离后,13种氨基酸NPP酯衍生物均可得到良好的基线分离。在样品量不低于20 ng N条件下,GC-C-IRMS方法的精密度优于1‰,测得的δ^(15)N值与EA-IRMS法测得的δ^(15)N值没有明显差异。阳离子树脂纯化前后各氨基酸δ^(15)N值差异低于1‰,表明没有产生明显的同位素分馏。采用本方法成功地估算了阿哈湖生态系统中常见水生生物的营养级,可作为研究氨基酸代谢以及生态系统特征的新方法。
